What if Buffy was Boba Fett? That’s the delicious premise of Killjoys, a sci-fi show about good-looking, trigger-happy bounty hunters who acknowledge that spaceships are cool but otherwise don’t get too hung up on the science part. At a time when the multiplex has offered up a series of thrill-free duffers like Transformers: The Last Knight, King Arthur and The Mummy, Killjoys – which returns for its third season tonight – is a big, exuberant dollop of summer blockbuster fun (albeit filmed in Canada on a fraction of the budget).

Killjoys also offers respite from the current heavy weather of prestige TV: think of it as a rollicking tequila slammer between episodes of elliptical head-wrecker Twin Peaks, The Handmaid’s Tale or that final season of The Leftovers. It’s a torrid summer fling waiting to happen, and while starting with season three is hardly advisable, the first series is available to dip into on Netflix. If you mourn the early cancellation of Firefly – and it seems a lot of people still do – Killjoys seems designed to scratch that Whedon itch. It’s sexy, heartfelt and fun.

Like Firefly’s ad-hoc family of space cowboys, Killjoys follows the misadventures of a quippy crew operating on the fringes of space and legality. As Reclamation Apprehension Coalition (RAC) agents – bounty hunters informally known as killjoys – the central trio of Dutch, Johnny and D’avin technically have badges to go with their guns, but do their best work outside any official framework. For a certain generation, the name Dutch brings to mind Arnie’s alien-bopping commando from Predator, and it seems like a deliberate move: Dutch is a similarly strong, fearless leader ready to deal with any close encounters. She’s also a woman, but that hardly seems the point.

Ready to deal with any close encounters … the Killjoys. Photograph: Syfy

Dutch is played by Hannah John-Kamen, a British actor with the distinction of having starred in two different episodes of Black Mirror. She glides through the grungy, cyberpunk future of Killjoys with feline grace, and amid a cast of US and Canadian actors, her faintly growly British accent makes her stand out even more. It’s a kick-ass central performance (even if she always makes a point of pronouncing it “arse”).

Her wingmen are the sparring Jaqobis brothers: Johnny (Aaron Ashmore) is the tech geek with a heart of gold and D’avin (the towering, sculpted Luke Macfarlane) is the meathead muscle. Killjoys is the sort of show that is self-aware enough to comment on and even define itself. As D’avin tells Dutch: “That’s what makes us a great team – you lead, I shoot, Johnny gives a shit.” But over the course of two seasons, those character templates have deepened and expanded, and all three of the core cast have developed some excellent comic timing.

The tech geek with a heart of gold … Johnny in Killjoys. Photograph: Syfy

In their talking spaceship Lucy, the Killjoys chase down targets in the Quad, a place where the social hierarchy is rigidly defined. Nine elite ruling families live in luxury on the fresh-aired planet of Qresh, while blue-collar miners choke on haphazardly terraformed nearby moons like Westerley. This frontier setting adds to the Firefly feel, and the production designers do a terrific job of turning corners of Toronto into Blade Runneresque bazaars. An overarching storyline about a conspiracy in the RAC means there’s some mythology to get your teeth into, but the guiding principle of showrunner Michelle Lovretta and her writer’s room simply seems to be: what would be fun? Perhaps that’s why Killjoys season three kicks off with an Eastern Promises-style fistfight in a space sauna.

In these sorts of shows, it usually doesn’t take long for an evil twin to turn up – and season two of Killjoys introduced the mysterious Aneela as a dual role for John-Kamen. This double Dutch storyline looks set to feature heavily in season three and it feels like a smart move as John-Kamen is poised to make a movie breakthrough by co-starring in the Tomb Raider reboot, Spielberg’s video game epic Ready Player One and Marvel’s upcoming Ant-Man sequel. Killjoys might be perfect backup blockbuster fun this summer, but next year John-Kamen will be doing it for real.

Killjoys season three starts tonight on Syfy UK, 9pm. Season one is available on Netflix US and UK.